How does the "Depth" property work in image objects?
Default : Displays like any regular 3d object, if another object obstructs it, it will not display. If it obstructs another object, the other object does not display.
Front : Always displays in front of other objects, even if the view is obstructed.
Back : It will always display behind other objects, even if they are placed in front of them.

Note that this kind of image objects are meant for reference only while modeling and setting the scene, they will not be visible in the rendered image. If you need the image to render then import it using &quot;import images as planes&quot; or use the compositor to set a background for the scene.